History
Severity of disease due to C diphtheriae depends on the site of infection, the immunization status of the patient, and the dissemination of toxin (which is influenced by administration of antitoxin). Initial infection usually is localized and is categorized by the site of involvement.
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Tonsils and pharynx: Tonsillar and pharyngeal diphtheria are most common; symptoms begin with a sore throat, usually in the absence of systemic complaints. Fever, if it occurs, is usually lower than 102°F, and malaise, dysphagia, and headache are not prominent features.
In individuals with diphtheria infection who are not immune, membrane formation begins after the 2-day to 5-day incubation period and grows to involve the pharyngeal walls, tonsils, uvula, and soft palate. The membrane may extend to the larynx and trachea, causing airway obstruction and eventual suffocation.
Underlying tissue of the throat and neck becomes edematous, and lymphadenopathy develops. Marked edema of the neck may lead to a bull-neck appearance with a distinct collar of swelling; the patient throws the head back to relieve pressure on the throat and larynx. Erasure edema associated with pharyngeal diphtheria obliterates the angle of the jaw, the borders of the sternocleidomastoid muscle, and the medial border of the clavicles. Swallowing may be made difficult by unilateral or bilateral paralysis of the muscles of the palate.
If toxin production is unopposed by antitoxin and severe disease occurs, early localized signs and symptoms give way to circulatory collapse, respiratory failure, stupor, coma, and death.
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Larynx: In a minority of patients, the larynx is the initial site of infection, with initial presenting symptoms similar to laryngotracheobronchitis from other causes. Initial hoarseness may progress to loss of voice and severe respiratory tract obstruction. Initially, nasal diphtheria may present as a common viral upper respiratory tract infection. A foul odor may develop. This form of diphtheria is most common in infants.
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Skin: Cutaneous diphtheria may occur at one or more sites, usually localized to areas of previous mild trauma or bruising. It is more common in tropical climates, but outbreaks have occurred in the United States. Pain, tenderness, and erythema at the site of infection progress to ulceration with sharply defined borders and formation of a brownish gray membrane. Local disease may persist for weeks to months.
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Other sites: Additional sites of infection have included the external ear, the eye (usually the palpebral conjunctivae), and the genital mucosa. Rare sporadic cases of endocarditis have been reported, usually due to nontoxigenic strains. Septicemia caused by C diphtheriae is rare but universally fatal.
Physical
Infection of the anterior nares (more common in infants) causes serosanguineous, purulent, erosive rhinitis with membrane formation. Shallow ulceration of the external nares and upper lip is characteristic. Mild pharyngeal infection is followed by unilateral or bilateral tonsillar membrane formation, which extends variably to affect the uvula, soft palate, posterior oropharynx, hypopharynx, and glottic areas. Underlying soft tissue edema and enlarged lymph nodes can cause a bull-neck appearance. The degree of local extension directly correlates with profound prostration, bull-neck appearance, and fatality from airway compromise or toxin-mediated complications. The leatherlike adherent membrane, extension beyond the faucial area, relative lack of fever, and dysphagia help differentiate diphtheria from exudative pharyngitis due to Streptococcus pyogenes and Epstein-Barr virus.
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Classic cutaneous diphtheria is an indolent nonprogressive infection characterized by a superficial, ecphymic, nonhealing ulcer with a gray-brown membrane. Diphtheritic skin infections cannot always be differentiated from streptococcal or staphylococcal impetigo, and they frequently occur together. In most patients, underlying dermatoses, lacerations, burns, bites, or impetigo have become contaminated secondarily. Extremities are affected more often than the trunk or head. Pain, tenderness, erythema, and exudate are typical. Local hyperesthesia or hypesthesia is unusual. Respiratory tract colonization or symptomatic infection and toxic complications occur in a minority of patients with cutaneous diphtheria.
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C diphtheriae occasionally causes mucocutaneous infections at other sites, such as the ear (otitis externa), eye (purulent and ulcerative conjunctivitis), and genital tract (purulent and ulcerative vulvovaginitis). Skin is the probable portal of entry, and almost all strains are nontoxigenic. Sporadic cases of pyogenic arthritis, mainly due to nontoxigenic strains, are reported in adults and children. Do not dismiss diphtheroids isolated from sterile body sites as contaminants without careful consideration of the clinical setting.
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Toxic cardiopathy occurs in approximately 10-25% of patients with diphtheria and is responsible for 50-60% of deaths.
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Neurologic complications parallel the extent of primary infection and are multiphasic in onset.
Causes
Among nonimmunized populations, diphtheria most often occurs during fall and winter, although summer outbreaks have occurred. Disease spreads more quickly and is more prevalent in poor socioeconomic conditions, where crowding occurs and immunization rates are low.
International travel could pose a risk to persons who are unvaccinated or inadequately vaccinated. The last case of fatal respiratory diphtheria in United States was reported in an unvaccinated Pennsylvania resident who had visited Haiti in October 2003. [6]
